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Questions tagged [newtonian-mechanics]

Newtonian mechanics covers the discussion of the movement of classical bodies under the influence of forces by making use of Newton’s three laws. For more general discussion of energy, momentum conservation etc., use classical-mechanics, for Newton’s description of gravity, use newtonian-gravity.

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At what amplitude is maximum tension produced? [closed]

While I was studying angular SHM, a question struck me. Suppose there were two masses $m$ connected by a light rod at a distance $\frac{l}{2}$ from the centre of the light rod. If the centre of the ...
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How fast would a machine have to throw a basketball in Argentina to make a score in Canada? [closed]

Giving that: a. The distance between Argentina and Canada is 11,252 km b. The official weight of a basketball is 20 ounces c. There's no air or wind or any kind d. The basketball is made of such a ...
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How do I relate angles with masses ratio? [closed]

Two masses, M and m, are connected by an inextensible string which passes over a frictionless pulley. Mass M rests on a frictionless slope, as shown. The slope is at an angle θ to the horizontal. The ...
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Conceptual question about wheels

I am trying to understand quite naively wheels in a specific framework. Intro We normally think of squares and circles as different concepts of shapes, but I am reframing it that both are polygons ...
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Work-Energy Problem: A ring pulley and mass system, in which the ring is sliding on a vertical rod [closed]

A heavy ring of mass $\;m\;$ slides on a smooth vertical rod and is attached to a light string which passes over a small smooth pulley distant $\; 'a' \;$ from the rod and has a mass $\;M(>m)\;...
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Prove this mathematical equation is useful in classical mechanics [closed]

Prove that this equation is being used in the proofs of classical mechanics. $$ \sum m_i\left(\dot{\vec r_i}\cdot\delta\dot{\vec r_i}\right)=\delta\sum\frac12m_i\left(\dot{\vec r_i}^2\right). $$
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Newton's Cradle doubt

I'm trying to learn physics, and I have a question regarding Newton's Cradle. I learned that momentum is conserved on a Newton's Cradle, and that momentum conservation is only for closed systems (no ...
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Does surface friction affect acceleration? [closed]

Lets say I have a cart moving on a straight friction less track. If I add friction to that track, will the acceleration decrease? My gut tells me it does. Because if there is friction present, then ...
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Do spring systems gain potential energy or stay the same?

I am trying to understand why the change in $E_{\mathrm{total}}$ of system BS is positive. Shouldn't it be the same since no energy is lost or gained? Also, can anyone explain how $\Delta U_g < \...
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1answer
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Reaction wheel: angular momentum conservation or action-reaction?

Reaction wheel are commonly used in spacecraft to change its attitude: an onboard inertia wheel is accelerated or decelerated along an axis to make the spacecraft rotate around the same axis. While ...
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Does all objects really fall with the same acceleration? [duplicate]

I know that acceleration due to gravity is independent of mass : $$a = \frac{F}{m} = G\frac{M}{r^2}$$ Meaning that a hammer and a feather fall with the same acceleration on the moon. I am confused, ...
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Railroad train on tracks [closed]

What keeps the railroad trains on the tracks? P.S: It is not the flanges, as already remarked by Dr. Richard Feynman. I want a detailed explanation of this question, if possible. Thanks.
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Kinetic energy always time independent?! Where is my mistake? [closed]

I have some problems understanding the Lagrangian and the Hamiltonian formalism. Those can be condensed in the following "derivation" of $\frac{\partial T}{\partial t} = 0$ from the equation $\frac{\...
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Where does the normal force in a vertical circular motion of a car in vertical road loop come from?

i have to use it in calculation but i am confused whether it is just used for simplification like centrifugal force? As there is no centrifugal force, the body is not pushing towards the edge of ...
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What is the rate at which a precessing top falls over?

From the following equation from hyperphysics, as rotational speed $\omega$ decreases, precession speed $\omega_p$ increases. However, from what we observe physically, as rotational speed of the top ...
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1answer
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Pulley in a lift [closed]

. This might be in an easy question.But in the the given figure we write mg -T = ma now suppose the lift is accelerating with 2 m/s^2 we get T = m(g-a)~m(6). now if the lift start accelerating/...
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Mechanism behind a simple pendulum [closed]

Show that the tension in a simple pendulum is of the form $$T(t)= T_0 + T_2 \cos(\omega t)$$ and find $T_0$ and $T_2$ in terms of the mass $m$ of the bob, the amplitude of the oscillation $θ_0$ ...
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Why gravitational mass and inertial mass being same was a problem before Einstein solved it?

Why is it so that Einstein is credited with telling us the reason for the equivalence of inertial and gravitational mass of an object? Did Newton ever make a distinction between the two masses? What ...
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A spacecraft orbiting the sun charges a battery which becomes a tiny bit more massive. How does this effect the velocity of the spacecraft

According to E=mc² the spacecraft which stores the Energy from the sun becomes a tiny bit more massive. how does this effect the impulse of this spacecraft. Would it grow because P = (m + extra mass) *...
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Friction converting into a heat

On my exam I had following question: bullet with mass $m$ and initial velocity $v_1$ hits wooden board of length $d$ and breaks it through. After that its velocity is $v_2$ and heat generated in a ...
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1answer
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Force measurement [closed]

We have a bike and a biker on it of mass 81 kg combined. Biker can reach speed around 30k/h. And the question is: how to measure the force (in Newtons) applied on the bike to reach that speed in 10 ...
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Why does the universe require relativity? [closed]

Are there any known compelling reasons why our universe is governed by relativity instead of Newtonian physics? I recognize that an infinite $c$ would be a problem, so I'm not asking about that; I ...
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101 views

Stuck in a mechanics problem [on hold]

The block is accelerating in horizontal direction towards right. By work energy theorem we have, $$W_P +W_G +W_N = \Delta K$$ $W_P$ is the work done by pseudo force in the frame of cylinder. The ...
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Angular momentum and external torque

In John Taylor - Classical mechanics it was mentioned that the equation $L' = \Gamma^{ext}$ is true even with respect to the center of mass. Here we are working with a system of particles, $L = \sum ...
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Why in a elongating string we can not use newton law

I am trying to solve this question using newton law $$ mg- kx = ma$$ When there is maximum elongation then a=0 $$mg=kx$$ $$x=mg/k$$ Here why i am getting different result?
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Tension in a string moving in elevator

A lift can move in $x$ axis and also in $y$ axis. A bob of mass m is suspended with inextensible thread inside the ceiling of elevator. Determine tension $T$ in the string when elevator moves in $x$ ...
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1answer
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Projectile coming to a full stop at impact versus breaking through and continuing on

In the following scenario neglect any deformation forces within materials and assume the collision is inelastic. There are no instances of rebounding of the projectile at impact. There is no flying ...
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Is the normal force always equal to the weight on an inclined ramp?

As the title states, my question is: Is the normal force always equal to the force of weight on an inclined ramp? As an extension of this, when we are solving problems involving "a block slides down ...
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1answer
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**Mathematical Derivation** of the fact that all planets will orbit on the same plane

There is some discussion about this Here. If an isolated system of particles under gravitational force is allowed to decrease its energy by means such as inelastic collision, then eventually all ...
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Why choosing for prime numbers eliminates vibration?

I have read that the spokes of a car wheel are usually five because, besides other substantial reasons, five being a prime number helps to reduce vibrations. The same also happens with the numbers of ...
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1answer
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What physical quantity remains equal in different frames? [closed]

I recently came across a problem which involved going into rotating frames. And it was pretty tiring. (And difficult..). So I wondered if there was some quantity that you could measure from the ground ...
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Experimental verification of Newton's laws

I came across this translation of Newton's Second Law: "The alteration of motion is ever proportional to the motive force impressed and is made in the direction of the right line in which the force ...
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Why does a scale measure the normal force and not the weight of an object?

I don't understand the reason scales measure the normal force instead of the weight.
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FBD of 4Kg block

In this diagram when we draw FBD of the 4Kg block will we write the force by earth (weight) as 4 kg or 10 kg .I believe it should be 10 as when FBD is drawn it should also contain wt. Of 6kg block as ...
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1answer
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Deriving equations of rotational motion for connected rods

I'm working on a problem involving deriving equations of rotational motion for a system of connected rods (see the picture), and I'm a bit confused about a few things to do with rotational motion. I ...
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How are these two versions of the conservation of angular momentum different?

Here are two versions of the conservation of angular momentum. The total angular momentum is constant if there is no external moment on the system The total angular momentum of a particle is constant ...
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Two Body Systems- doubts

I was self-teaching Two Body Problem using Symon's Mechanics (3rd Edition) but I am stuck with two questions. On page 185, the total angular momentum of system is given to be \begin{equation} \...
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1answer
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Conservation of mechanical energy proof (Kleppner Kolenkow)

On page 168 of Kleppner and Kolenkow's mechanics they give a proof of the conservation of mechanical energy theorem which starts roughly as follows: The work done by a conservative force depends only ...
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Calculating Vx and Vy given V, X, Y

I have a problem where I am given a trajectory by x(t), y(t) and I am given a constant speed throught the whole trajectory. I need to find vx and vy. Equations that I am given: x(t) = 1.5 + 0.5 * t *...
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Axiomatic classical mechanics

I am looking for a book that axiomatizes classical (meaning Newtonian) mechanics, as some books do with special relativity. I would be very interested in reading such a book.
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How to calculate the normal modes from a given potential?

I have a potential of the form: $U=\frac{1}{2}\omega_{0}^{2}(x_{1}^{2}+x_{2}^{2})-\alpha x_{1}x_{2}$ How can I find the normal modes of this potencial? Should I expect solutions of harmonic oscilator ...
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If reference frames are coordinates system then is the motion of bodies analysed through graphs

If we imagine a body moving at constant velocity "v".now if we want to represent in frame of reference what would we do 1)draw graph for this 2)draw a coordinate system and represent the body
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Can someone explain the coeffieient of restitution and how inelastic collision results in momentum but not kinetic energy being conserved?

Can anyone explain how the coefficient of restitution is related to inelastic collisions? How can non-conservation of kinetic energy be true taking the equations of kinematics and conservation of ...
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1answer
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Why a coin feels a force when it is put on a rotating horizontal disc

Suppose we have a disc which is placed in horizontal plane and have radius R. Disc is rotating and rotation axis is passing through center of disc and in vertical plane . Now we place a coin a on disc ...
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Calculating the velocity of ejecta from an asteroid impact

Somewhat naively, I'm trying to figure out how to create a very basic model of collisions between celestial bodies and the nature of the ejecta clouds produced by such impacts. Say, for example, ...
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3answers
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Work Done by Running Up Stairs

This problem is from "the Physics Classroom": During the Powerhouse lab, Jerome runs up the stairs, elevating his 102 kg body a vertical distance of 2.29 meters in a time of 1.32 seconds at a constant ...
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Applying newton's second law on circular motion

In school, when we are studying circular motion, we analyse the forces acting on the body into two axis, the tangential one to the speed of the body and the perpendicular one and then we apply newton'...
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1answer
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Is there a normal velocity of water flowing on a curved surface?

Is there a normal velocity of water flowing on a curved surface? If so, will this normal velocity cause water to be pulled? If so, will this pull reduce the pressure on the curved surface? Flowing ...
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1answer
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Will extracting power from ocean tides affect the moon's orbit in the LONG run?

Conservation of energy says that any energy extracted from our ocean's tides would have to come from somewhere. Since these tides are a gravitational effect due to the moon, it would seem that the ...
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Can we find the value of impulsive tension?

Suppose a ball is attached to a string of length $l$ and the string is attached to the ceiling. Now when I keep the ball close to the point of suspension and release it, it will travel a distance $l$ ...